Processing mail with automated equipment at mail processing centers requires correctly orienting the mail so that address information and other related information can be scanned and read. This process is known as facing and is accomplished with facing equipment that is typically part of the Advanced Facer Canceller System (AFCS) equipment in the United States Postal service (USPS) sorting systems. Additionally, a discriminating canceller detects the type of postage evidencing used and cancels stamps by marking over the stamp with a cancellation mark so that the stamps cannot be reused. Other forms of postage payment evidencing such as postage meter indicia and permit mail marks are not typically canceled.
The AFCS system includes a short UV excitation source (254 nm) that is used to excite certain luminescent inks. Certain fluorescent luminescent inks radiate light in a particular wavelength such as the visible spectrum during excitation by a particular source such as a UV source. Certain phosphorescent luminescent inks radiate light in a particular wavelength such as the visible spectrum during and after excitation by a particular source such as a UV source. Both type of luminescent inks described can be used for signaling since the radiated light can be detected by a photo-detector tuned to detect radiation in the particular radiated frequency range. As described herein, the AFCS utilizes several different signaling methods to detect postage payment evidencing marks for facing purposes, but the canceller searches for a green phosphorescent signal to initiate the canceling system.
Currently, postage stamps emit a green phosphorescent signal in response to the AFCS excitation source that is detected by the facer portion of the system and used for mail piece orientation (facing). Additionally, the green phosphorescent signal from the stamp is also used by the canceller portion of the equipment to trigger stamp cancellation. The stamp is typically cancelled by canceling equipment so that it cannot be used again and may also provide information such as the date of processing or induction in the postal system. Such cancellation is typically accomplished by printing a black mark across the stamp that may include induction date information and induction post office location information.
Other postage payment evidencing system such as postage meter indicia and permit mail typically utilize different facing signaling mechanisms that are not detected by the canceller since it is not desirable to cancel postage meter indicia. Traditional postage meter indicia marks utilize visible red fluorescent ink that emits a red fluorescent signal when excited by the UV source. Such red fluorescent signal is utilized by the facing system to detect the indicia, but does not trigger the canceller that is searching for green phosphorescent signals. Traditional permit mail postage payment marks include a Facing Identifier Mark (FIM) barcode used for facing purposes. The facing system detects the barcode using a barcode reader and the barcode does not trigger the canceller. However, these methods can significantly affect the final appearance of the image. Using a FIM requires printing a large barcode in a particular portion of the envelope and thus imposes significant restrictions on what can be printed. Many postage meters utilize ink jet printing to print fluorescent indicia.
More recently, other forms of postage payment evidencing have been utilized including custom stamps and custom image stamps. Such postage payment evidencing products include products that may be printed locally by a consumer using controlled media stock or other stock and also include products that may be custom configured and then centrally printed and shipped to a consumer. In the case of custom image postage evidencing products that include custom images such as baby pictures, it is not considered desirable to cancel such products. Certain custom postage evidencing systems utilize thermal media such as direct contact thermal printing media labels to print postage indicia.
As described, the AFCS facer/canceller equipment uses a short UV excitation source in order to detect a luminescent response from the mail piece. The equipment has at least three detection channels, two of which are used and one of which is unused. There is a green phosphorescent range channel that is used by both the facer/canceller to both face and cancel postage stamps, a red fluorescent range channel that is used to face traditional postage meter indicia. Additionally, there are certain postage indicia label stamps that utilize a visible red fluorescent facing mark that also utilizes the red fluorescent detection channel. There is a red phosphorescence detection channel that is sometimes considered unused in postal specifications, but that current commercially available custom stamp products utilize for detection in the facer equipment. Unfortunately, such custom stamp products utilizing the red phosphorescent channel can result in cancellation of the custom image thereby defeating the purpose of having custom stamp images available for viewing by the recipient.
When the USPS AFCS facer/canceller equipment operates in the USPS sorting equipment stream, the equipment emits a short UV radiation of approximately 254 nm wavelength that is used to excite the face of the mail piece. As described, in the case of phosphorescent stamps, the USPS facer/canceller equipment is calibrated to detect responses to that short UV excitation in a particular range. Additionally, the canceling systems used by the USPS in postal processing detect the phosphorescence signals in order to cancel them. Similarly, the AFCS equipment is calibrated to also detect a red fluorescent response in a particular range. There are known visible red fluorescent inks that do not appreciably emit phosphorescent responses that are detectable by the canceller. However, it may be desirable to have an invisible fluorescent ink that triggers the red fluorescent detection channel, but that does not trigger the phosphorescent channel detected by the canceller. The green detection channels detect certain intensities in approximately the 495 nm-560 nm range and the red channels detect certain intensities in approximately the 560 nm-650 nm range. The USPS LM-2C Phosphor Meter Unit (PMU) test system is typically utilized to test expected response in the AFCS system.
Invisible ink jet inks are described in U.S. patent application Ser. No. 10/331,829 filed Dec. 30, 2002 which is hereby incorporated by reference in its entirety. Color fluorescent inks are described in U.S. patent application publication Nos. US 2002/0195586 A1, US 2003/0005303 A1, and US 2003/0041774 A1, which are hereby incorporated by reference in their entireties. Color luminescent ink, such as a fluorescent ink or a phosphorescent ink is described in U.S. patent application Ser. No. 10/692,569 filed Oct. 24, 2003, which is hereby incorporated by reference in its entirety.
There is a need for a thermal media label stock that provides a fluorescent signature used in postal facing systems. Similarly, there is a need for a thermal media label stock having an invisible ink coating or partial coating that provides a sufficient red fluorescent signature to trigger the AFCS facing system but that does not emit a phosphorescent signal that triggers the USPS AFCS canceller systems. Additionally, there is a need for a thermal media label having such an invisible red fluorescent ink coating that will reliably function in a direct contact thermal media printer and not “block” or jam when being fed through a printing thermal media print head.
Furthermore, there is a need for a thermal media label having such an invisible fluorescent ink coating such that the coating will not be removed in the printing process thus fouling the printer. Additionally, there is a need for such an invisible red fluorescent ink formulation using a varnish providing an ink that may adequately be applied in an appropriate coating process such as a flexographic printing process. Furthermore, there is a need for such an invisible red fluorescent ink formulation using a varnish that suitably adheres to the thermal media and remains on the thermal media throughout the direct contact thermal printing process yet does not unacceptably quench the fluorescent signal of the pigment in the ink.